The water in swimming pools is often contaminated by foreign substances, including for example, tree branches, leaves, bacteria, and fungus. Such contamination can stain the side walls and other surfaces of the pools, and such stains can be quite difficult to remove.
U.S. Pat. No. 4,906,384 to Hamilton (Mar. 6, 1990) teaches the use of acids to remove scale deposits and stains from the sides of swimming pools, and U.S. Pat. No. 5,071,569 to Caulfield et al. (Dec. 10, 1991) teaches the use of EDTA compounds and ammonium ions to removing algae stains. These and all other extrinsic materials discussed herein are incorporated by reference in their entirety. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
Some formulas combine stain removing compositions with sanitizing compositions. For example U.S. Pat. No. 6,562,243 to Sherman (May 13, 2003) teaches a formula that combines oxidizing agents (chlorine) with algaecides. Unfortunately, the level of chlorine that is appropriate for a swimming pool can take days or even weeks to provide adequate stain removal. The problem is compounded because different swimming pool chemicals can interfere with each other. An addition of too much sodium bromide to a swimming pool, for example, can destabilize chlorine, requiring an even greater addition of chlorine to cleanse the pool.
Thus, there is still a need for swimming pool chemical formulas that provide both rapid stain removal and effective antimicrobial action.